# US 4,394,073 A · Compact wide angle lens > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,394,073 A - Document ID: US4394073A - Status: Granted - Kind: A - Application number: 06/214,887 - Filed: 1980-12-10 - Granted: 1983-07-19 - Earliest claimed: 1979-12-28 - Assignees: Nippon Kogaku K.K. - Inventors: Koichi Wakamiya - Web page: https://patentgrep.com/patent/US4394073A ## CPC - G02B 9/60: having five components only - G02B 13/04: Reversed telephoto objectives - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A compact wide angle lens comprises, in succession from the object side, a first component which is a positive meniscus lens having its convex surface facing the object side, a second component which is a biconcave lens, a third component which is a positive lens having its surface of sharper curvature facing the object side, a fourth component which is a positive lens, and a fifth component which is a negative meniscus lens having its convex surface facing the image side. ## Claims ### Claim 1 A compact wide angle lens system having an angle of view of 60.degree.-70.degree. and a total length as short as the total focal length, f, of the lens system, comprising, in succession from the object side, a first positive meniscus lens component having its convex surface facing the object side, a second biconcave lens component, a third positive lens component having its surface of sharper curvature facing the object side, a fourth positive lens component, and a fifth negative meniscus lens component having its convex surface facing the image side, the lens system satisfying the condition: 0.51f<f.sub.4 <1.38f where f.sub.4 represents the focal length of said fourth component. ### Claim 2 (depends on 1) A compact wide angle lens system according to claim 1, further satisfying the following conditions: 0.57<f.sub.1 <0.74f d.sub.8 <0.15f 0.02f<d.sub.6 <0.12f where f.sub.1 represents the focal length of said first component, d.sub.6 represents the air space between said third component and said fourth component, and d.sub.8 represents the air space between said fourth component and said fifth component. ### Claim 3 (depends on 2) A compact wide angle lens system according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62.degree. ______________________________________ r.sub.1 = 33.422 d.sub.1 = 8.570 n.sub.1 = 1.77279 .nu..sub.1 = 49.4 L.sub.1 r.sub.2 = 86.715 d.sub.2 = 5.713 r.sub.3 = -193.623 d.sub.3 = 2.857 n.sub.2 = 1.78470 .nu..sub.2 = 26.1 L.sub.2 r.sub.4 = 44.440 d.sub.4 = 4.571 r.sub.5 = 38.296 d.sub.5 = 9.998 n.sub.3 = 1.62374 .nu..sub.3 = 47.0 L.sub.3 r.sub.6 = 108.753 d.sub.6 = 4.285 r.sub.7 = 92.359 d.sub.7 = 11.141 n.sub.4 = 1.80740 .nu..sub.4 = 35.4 L.sub.4 r.sub.8 = -131.181 d.sub.8 = 12.283 r.sub.9 = -22.687 d.sub.9 = 2.857 n.sub.5 = 1.78797 .nu..sub.5 = 47.5 L.sub.5 r.sub.10 = -42.682 .SIGMA.d = 62.274 wherein: Back focal length: Bf = 40.415 Total length: T.L. = 102.689 = 1.027f f.sub.1 = 65.8 = 0.658f f.sub.4 = 68.7 = 0.687f f.sub.12 = -539.6 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and .nu. represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f.sub.12 represents the combined focal length of the first and second components. ### Claim 4 (depends on 2) A compact wide angle lens system according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62.degree. ______________________________________ r.sub.1 = 32.280 d.sub.1 = 8.570 n.sub.1 = 1.77279 .nu..sub.1 = 49.4 L.sub.1 r.sub.2 = 76.797 d.sub.2 = 5.713 r.sub.3 = -203.021 d.sub.3 = 2.857 n.sub.2 = 1.78470 .nu..sub.2 = 26.1 L.sub.2 r.sub.4 = 42.069 d.sub.4 = 4.571 r.sub.5 = 36.999 d.sub.5 = 9.998 n.sub.3 = 1.62374 .nu..sub.3 = 47.0 L.sub.3 r.sub.6 = -8133.457 d.sub.6 = 9.141 r.sub.7 = 100.449 d.sub.7 = 5.428 n.sub.4 = 1.80740 .nu..sub.4 = 35.4 L.sub.4 r.sub.8 = -592.361 d.sub. 8 = 10.284 r.sub.9 = -22.130 d.sub.9 = 2.857 n.sub.5 = 1.78797 .nu..sub.5 = 47.5 L.sub.5 r.sub.10 = -40.439 .SIGMA.d = 59.417 wherein: Back focal length: Bf = 40.387 Total length: T.L. = 99.804 = 0.998f f.sub.1 = 66.5 = 0.665f f.sub.4 = 106.7 = 1.067f f.sub.12 = -388.0 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and .nu. represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f.sub.12 represents the combined focal length of the first and second components. ### Claim 5 (depends on 2) A compact wide angle lens according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62.degree. ______________________________________ r.sub.1 = 32.565 d.sub.1 = 8.570 n.sub.1 = 1.78100 .nu..sub.1 = 44.5 L.sub.1 r.sub.2 = 74.220 d.sub.2 = 5.713 r.sub.3 = -204.935 d.sub.3 = 2.875 n.sub.2 = 1.78472 .nu..sub.2 = 25.7 L.sub.2 r.sub.4 = 42.997 d.sub.4 = 4.571 r.sub.5 = 38.167 d.sub.5 = 2.857 n.sub.3 = 1.62374 .nu..sub.3 = 47.0 L.sub.3 r'.sub.5 = 30.280 d'.sub.5 = 7.142 n.sub.4 = 1.62230 .nu.'.sub.3 = 53.1 r.sub.6 = -2093.039 d.sub.6 = 7.999 r.sub.7 = 105.514 d.sub.7 = n.sub.5 = 1.79504 .nu..sub.4 = 28.4 L.sub.4 r.sub.8 = -458.112 d.sub.8 = 10.284 r.sub.9 = -22.159 d.sub.9 = 2.857 n.sub.6 = 1.78797 .nu..sub.5 = 47.5 L.sub.5 r.sub.10 = -39.381 .SIGMA.d = 61.417 wherein: Back focal length: Bf = 40.223 Total length: T.L = 101.640 = 1.016f f.sub.1 = 68.1 = 0.681f f.sub.4 = 108.6 = 1.086f f.sub.12 = -374.9 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and .nu. represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f.sub.12 represents the combined focal length of the first and second components. ### Claim 6 (depends on 1) A compact wide angle lens system according to claim 1, wherein the second lens component is formed of high dispersion flint glass.